Color-tinted lenses have been developed for goggles and glasses to reduce light transmission and to mitigate glare. In certain sports,-such as skiing and snowboarding, glare reduction is especially desirable. Lenses with a graded tint have been found to reduce glare also, and are especially useful for sports which require a clear view of proximal terrain and objects yet a reduced glare when viewing distant terrain or objects.
Polycarbonate is a useful lens material for sports goggles and glasses because it is strong, durable and lightweight; however, it is not necessarily highly mar-resistant. Polycarbonate may be compounded with a dye, for example a fabric dye, so as to exhibit a uniform color tint when formed into a film. Unfortunately, this process does not lend itself to achieving a graded tint in the polycarbonate medium.
In order to impart mar-resistance to a polycarbonate lens, formable mar-resistant protective coatings, e.g., melamine formaldehyde, have been employed. Melamine formaldehyde coatings have the advantage that they can be formed with a graded tint, although with some difficulty. Unfortunately, such coatings made of melamine formaldehyde are not chemically durable when exposed to some lens cleaning and other chemical agents.
There have been developed more chemically durable and inert mar-resistant coatings for polycarbonate. Unfortunately, because they are so chemically inert, no practical methods have been developed to color-dye those coatings, especially to provide a graded tint.
It is therefore desirable to provide a method of forming a tinted polycarbonate lens for glasses or goggles, and especially such a lens with a graded tint. Such a lens may, in addition, be coated with a highly mar-resistant chemically inert clear coating.